Systematic analysis on the primary radiation damage in Th_1−xU_xO₂ fluorite systems

Primary radiation damage featuring rapid atomic collisions and thermal spikes constitutes the foundation of a high-fidelity description of radiation-assisted microstructure evolution. To systematically describe the primary damage in the mixed fuel oxide systems Th_1−xU_xO₂, we consider the effect of temperature, composition, and primary-knock atom energy on defect generation. A holistic functional form is developed to effectively quantify the number of defects, and the exponential truncated power-law can well describe the defect size distribution. Furthermore, the defect (cluster) structures are elaborated, where notably vacancy clusters approach being charge balanced, and interstitial clusters can embrace a high symmetry with a cuboctahedral structure. These results present both a high-level description and a detailed atomic understanding towards radiation-induced defects in fuel oxides, which provides the required input for meso-scale simulations of microstructure evolution.